Heat stress induces a developmental shift from type-V to type-IV trichome dependent on jasmonate signaling in tomato

Abstract

AbstractCultivated tomato (Solanum lycopersicum) and related wild species develop several types of trichomes, both glandular and non-glandular, on their aerial parts. Among these, type-IV trichomes are responsible for the synthesis and secretion of acylsugars, which act as defense compounds against herbivores. In contrast to related wild species such asS. pennellii, type-IV trichomes are present only in the juvenile stages of cultivated tomato plants and absent in later stages of development. By submitting tomato plants to high temperatures during the day (37 °C), we observe that non-glandular type-V trichomes are replaced by type-IV trichomes. This is accompanied by a massive increase in acylsugar production. On the other hand, heat treatment does not affect type VI-trichomes, which produce mono- and sesquiterpenes, but the production of monoterpenes is increased while that of sesquiterpenes is suppressed. Furthermore, tomatojai1mutants deficient in jasmonate (JA) perception do not exhibit this developmental switch from type-V to type-IV trichomes. The implication of JA signaling in this process was further supported by an increase in JA-isoleucine and in the expression of genes involved in JA-signalling within hours of heat stress application. These results establish a unique system to study how environmental factors affect developmental fate decisions in plants while opening opportunities to understand mechanisms controlling type-IV trichome initiation and development.